The present invention relates generally to anti-armor weaponry, and more particularly to kinetic energy projectiles having fins which are arranged and adapted to be ejected from the projectile body on impact with the target.
Typically, kinetic energy projectiles are launched from gun tubes of tanks or other weaponry tubes against enemy tanks or other hard targets to cause total, or at least partial destruction and thereby disable the target. Damage to the target is caused solely by the kinetic energy (1/2.times.mass.times.velocity.sup.2) of the projectile, because the projectile contains no explosive charge. Such projectiles are fin-stabilized, and therefore, are designed to maintain a flat target trajectory with high velocity (usually Mach 5 or higher, equal to 5500 feet per second, approximately, at sea level) for short flight durations (e.g., from one to three seconds). By the time impact occurs, the projectile has been heated to sufficiently high temperature as a result of its velocity, shape and travel distance. The force of the impact tends to cause the projectile to penetrate the target structure at the point of impact and to cause the target to disintegrate into fragments capable of igniting the impacted tank's fuel and shells. A direct hit will usually cause an explosion or sufficient damage to be disabling, even if the target is not completely destroyed.
FIG. 1 shows a typical prior art kinetic energy projectile 10. The body 11 has a relatively large overall length to diameter (L/D) ratio and the forward portion 12 of the body is usually pointed. The projectile has surface groovings 13 and at least one set of multiple fins 14. The fins reduce the total armor penetration depth of this type of weaponry because of the direct physical obstruction at impact with the target. Nevertheless, fins are essential for in-flight stabilization of the projectile motion. Consequently it has been necessary to sacrifice some of the destructive force of the projectile attributable to the presence of the fins, for the sake of assuring accurate hits while seeking to reduce the pitching and/or yawing (lateral) motion of the projectile in flight which may cause oblique (instead of head-on) impact with the target.
It is desirable to increase the L/D ratio of the projectile, to increase its lethality; but it is not unusual for longer L/D projectiles to suffer decreased depth of penetration of the target because of rod bending of the projectile body at even small oblique angles of impact. The prevalence and extent of bending of the longer L/D (e.g., ratios greater than 20) projectiles is exacerbated with fins of heavier mass, causing a cantilever-type of body bending and even less target penetration. It would be desirable to reduce the fin mass or even to eliminate the fins altogether, if this could be done without sacrificing in-flight stability of the projectile, to reduce the body bending and increase the penetration depth of long L/D projectiles, thereby enhancing the lethality of the weapon.
It is a principal object of the present invention to increase the lethality of finned kinetic energy projectiles by achieving deeper penetration.
In the past, penetration of the target by the projectile body has been accompanied by use of fins of lighter weight or lighter density, such as aluminum rather than steel. However, such lower density fin materials are vulnerable to the aerodynamic heating associated with high launch speeds exceeding Mach 5 which otherwise could further enhance penetration and improve the ballistics and accuracy of the projectile.
It is a more specific object of the present invention to improve penetration of the kinetic energy projectile body into the target by providing the projectile with fins that are designed to withstand high velocity launch temperatures, exhibit lower drag force in flight, and be ejected upon impact of the projectile with the target.